:root {
    --primary-color: #4a90e2;
    --secondary-color: #50e3c2;
    --background-color: #f8f9fa;
    --text-color: #333;
    --card-bg: #ffffff;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --font-family: 'Poppins', sans-serif;
}

body {
    font-family: var(--font-family);
    background-color: var(--background-color);
    color: var(--text-color);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.page-wrapper {
    flex: 1;
    display: flex;
    flex-direction: column;
}

.main-content {
    flex: 1;
    padding-top: 2rem;
    padding-bottom: 2rem;
}

.navbar {
    box-shadow: 0 2px 4px var(--shadow-color);
}

.navbar-brand {
    font-weight: 600;
    color: var(--primary-color) !important;
}

.footer {
    box-shadow: 0 -2px 4px var(--shadow-color);
}

.card {
    border: none;
    border-radius: 10px;
    box-shadow: 0 4px 12px var(--shadow-color);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
}

.card-header {
    background-color: transparent;
    border-bottom: 1px solid #eee;
    font-weight: 600;
}

.btn-primary {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
    transition: background-color 0.2s ease, border-color 0.2s ease;
}

.btn-primary:hover {
    background-color: #357abd;
    border-color: #357abd;
}

.form-control,
.form-select {
    border-radius: 8px;
    border: 1px solid #ddd;
    padding: 0.75rem 1rem;
}

.form-control:focus,
.form-select:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 0.25rem rgba(74, 144, 226, 0.25);
}

.priority-badge {
    font-size: 0.8rem;
    padding: 0.4em 0.8em;
    border-radius: 20px;
    color: #fff;
    font-weight: 500;
}

.priority-high {
    background-color: #e74c3c;
}

.priority-medium {
    background-color: #f39c12;
}

.priority-low {
    background-color: #2ecc71;
}

.status-badge {
    font-size: 0.8rem;
    padding: 0.4em 0.8em;
    border-radius: 20px;
    color: #fff;
    font-weight: 500;
}

.status-todo {
    background-color: #3498db;
}

.status-in_progress {
    background-color: #9b59b6;
}

.status-completed {
    background-color: #1abc9c;
}

.empty-state {
    text-align: center;
    padding: 4rem 1rem;
    background-color: var(--card-bg);
    border-radius: 10px;
    box-shadow: 0 4px 12px var(--shadow-color);
}

.empty-state i {
    font-size: 4rem;
    color: #ccc;
}

.empty-state h4 {
    margin-top: 1.5rem;
    font-weight: 600;
}

.empty-state p {
    color: #888;
}

.completed-task {
    opacity: 0.7;
    position: relative;
    overflow: hidden;
}

.completed-task::after {
    content: '完成';
    position: absolute;
    top: 10px;
    right: -30px;
    background-color: #28a745;
    color: white;
    padding: 5px 30px;
    font-size: 12px;
    font-weight: bold;
    transform: rotate(45deg);
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
}